DLP Projector lenses - is hacking throw ratio possible?

Discuss about cameras, projectors, calibration panels, turntables etc.
mading
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Joined: 31 Jan 2017, 13:09

DLP Projector lenses - is hacking throw ratio possible?

Post by mading »

I would like to start a discussion regarding projectors.
Cameras and lenses are quite easy to find, they work out of the box.
They have a variety of features, pros and cons.

Consumer DLP/LCD/Laser/LED/Halogen... projector are used most of the times without modifications.
Lenses are often the weak ring in the chain, and probably the hardest to mod.
(yes: color wheel, kind of light source, etc.. all have their impact).

But the biggest issue I have found is the fixed throw ratio, too long minimum focus distance, poor focus and lens quality, etc...

I got the idea to start this thread following a discussion that started in a Micr0 thread:
https://www.3dscanforum.org/viewtopic.p ... 3&start=10

My wish: to add a tele zoom to my LGPF50KS or a PF1500 I can use to create a multi-FVO (with 3 lenses: 12-16-25 mm) scanner.
Something like the RangeVisionPro (which I suppose is using a zoom projector lens) or HDI Advance (which I don't).
As an alternative, I will consider using three lenses for the projector.
This will help (if I am not in mistake) keeping a similar camera distance and reducing the scanner dimensions.

Polyga is selling a development scanner that uses a TI DLP projector:
https://www.polyga.com/evm-3d-scanner-kit/

People watching films often looks for the opposite: reducing throw ratio:
https://www.avsforum.com/threads/wide-a ... or.378751/
https://www.instructables.com/Turn-a-Re ... hrow-Mode/
(notice the distorsion when usins additional lenses)

So if anybody has good thought based on optical theory and experience, the community of DIY will thank you!
LG PF50, LG PF1500, RangeVision DIY: 2x DahengMer630, 2X12 and 2X16 mm 5Mp ZK lenses, RV turntable
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OBNRacerMan
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Location: Obninsk, Russia

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by OBNRacerMan »

I've tried using a regular "third-hand" lens.
My "third-hand" lens :-)
My "third-hand" lens :-)
From a distance of 300mm, my projector produced a projection size of 230x130mm (as native size).
Distance 300mm, no lens, size 230x130mm
Distance 300mm, no lens, size 230x130mm
With this lens (from the same distance), the projection size was 150x90mm (which is almost twice the size without the lens (80x50mm) at a projection distance of 100mm). But with the lens there are problems with geometric distortions (but I think that they can be reduced somewhat by using a lens of a larger diameter).
Distance 300mm, with lens, size 150x90mm
Distance 300mm, with lens, size 150x90mm
P.S. The main problem is the selection of lenses ... unfortunately, I do not have familiar opticians who have the necessary knowledge and formulas ... so I have to experiment with everything that falls into my hands :cry:
Soft: RangeVision DIY, Calibration panel/Rotary tables - RangeVision, Prj: LG PF1500G, Cam: Daheng Mercury MER2-630-60U3M-L (USB3.0, monochrome) x2, Obj: ZLKC FM12036MP5 (F2.8/5Mp/12-36mm) x2. And a handheld scanner Creality Ferret
Alonso
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Joined: 05 Dec 2016, 05:55
Location: USA

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by Alonso »

It's just physics and a little bit of math! :mrgreen:
mading
Posts: 307
Joined: 31 Jan 2017, 13:09

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by mading »

An under 1k projector will be very interesting.

I was looking at Texas Instruments evaluation boards:
https://www.ti.com/dlp-chip/display-and ... arted.html
that's very informative.

A few evaluation board availables!
https://www.ti.com/dlp-chip/display-and ... pment.html

That's an example around 1K.
I don't understand if the optics can be changed.
https://www.digikey.it/product-detail/i ... ND/7219324
LG PF50, LG PF1500, RangeVision DIY: 2x DahengMer630, 2X12 and 2X16 mm 5Mp ZK lenses, RV turntable
mading
Posts: 307
Joined: 31 Jan 2017, 13:09

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by mading »

Alonso wrote: 29 Jan 2021, 20:15 It's just physics and a little bit of math! :mrgreen:
feel free to contribute with your own equations! :-)
LG PF50, LG PF1500, RangeVision DIY: 2x DahengMer630, 2X12 and 2X16 mm 5Mp ZK lenses, RV turntable
mading
Posts: 307
Joined: 31 Jan 2017, 13:09

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by mading »

Yes!
A turnaround for getting smaller FOV.
Somebody just moved the lens far from the DLP to get a smaller FOV for DLP resin printing:
Minimum FOV.jpg
https://packet39.com/blog/2016/02/03/mo ... d-printer/
LG PF50, LG PF1500, RangeVision DIY: 2x DahengMer630, 2X12 and 2X16 mm 5Mp ZK lenses, RV turntable
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Micr0
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Joined: 15 Nov 2016, 15:20
Location: New York City

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by Micr0 »

mading wrote: 29 Jan 2021, 20:49 Yes!
A turnaround for getting smaller FOV.
Somebody just moved the lens far from the DLP to get a smaller FOV for DLP resin printing:
Minimum FOV.jpg

https://packet39.com/blog/2016/02/03/mo ... d-printer/
The key here is finding a projector that you can get to the lens mounts without having to take anything else apart. This seems to be easier on older bigger projectors.
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Micr0
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Location: New York City

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by Micr0 »

OBNRacerMan wrote: 29 Jan 2021, 20:05 I've tried using a regular "third-hand" lens.
IMG_20210129_225036s.jpg

From a distance of 300mm, my projector produced a projection size of 230x130mm (as native size).
IMG_20210129_224558s.jpg

With this lens (from the same distance), the projection size was 150x90mm (which is almost twice the size without the lens (80x50mm) at a projection distance of 100mm). But with the lens there are problems with geometric distortions (but I think that they can be reduced somewhat by using a lens of a larger diameter).
IMG_20210129_224802s.jpg

P.S. The main problem is the selection of lenses ... unfortunately, I do not have familiar opticians who have the necessary knowledge and formulas ... so I have to experiment with everything that falls into my hands :cry:
I've tried those lenses but they seem to introduce too much distortion into the projected image.
µ
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OBNRacerMan
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Location: Obninsk, Russia

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by OBNRacerMan »

Micr0 wrote: 30 Jan 2021, 15:26 I've tried those lenses but they seem to introduce too much distortion into the projected image.
It is possible that large diameter lenses will help reduce distortion. I tried - the further I put the lens from the projector, the smaller I can get the picture size. But due to the small diameter of the lens, at such a distance, it no longer captures the entire light beam.

Or approach the alteration radically, and make changes to the design of the projector ...
Soft: RangeVision DIY, Calibration panel/Rotary tables - RangeVision, Prj: LG PF1500G, Cam: Daheng Mercury MER2-630-60U3M-L (USB3.0, monochrome) x2, Obj: ZLKC FM12036MP5 (F2.8/5Mp/12-36mm) x2. And a handheld scanner Creality Ferret
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Micr0
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Location: New York City

Re: DLP Projector lenses - is hacking throw ratio possible?

Post by Micr0 »

OBNRacerMan wrote: 30 Jan 2021, 20:08
Micr0 wrote: 30 Jan 2021, 15:26 I've tried those lenses but they seem to introduce too much distortion into the projected image.
It is possible that large diameter lenses will help reduce distortion. I tried - the further I put the lens from the projector, the smaller I can get the picture size. But due to the small diameter of the lens, at such a distance, it no longer captures the entire light beam.

Or approach the alteration radically, and make changes to the design of the projector ...
I can see in the pictures you posted the pincushioning of the image with the lens. Were you able to get good scans using that aux lens?
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